Ink jet recording is a process of ejecting ink as small droplets through minute nozzles to record letters and figures on surfaces of recording media. The ink jet recording processes that have come in practice include a process of converting electric signals to mechanical signals with electrostrictive elements, thereby intermittently ejecting inks stored in nozzle head portions to record letters and figures on surfaces of recording media, and a process of rapidly heating inks stored in nozzle head portions at parts very close to ejection portions to generate bubbles, and intermittently ejecting the inks by volume expansion due to the bubbles to record letters and figures on surfaces of recording media.
As for feeding of inks in ink jet recording, a process of using an ink set in which a plurality of inks different in colors are combined has been known. Such an ink set has the advantage that the type and ejection rate of each ink ejected from the ink set are selected on demand according to signals based on image information, thereby being able to easily obtain high-quality color images.
In general, inks in which various water-soluble dyes are dissolved in aqueous media have been widely used as the inks contained in such an ink set. Recently, however, inks in which pigments are dispersed in aqueous media with dispersing agents have also been provided. This is because the inks using the pigments (hereinafter also referred to as the pigment inks) are characterized by excellent weather resistance (such as water resistance or light resistance), compared to the inks using the water-soluble dyes.
However, according to the ink set having the pigment inks that have hitherto been known, it has been impossible to obtain good image quality without depending on the type of paper (particularly, whether paper exclusive to ink jet recording or plain paper).